Grease star Dame Olivia Newton-John has passed away aged 73, after a long battle with breast cancer. Her husband, John Easterling, said the British-born singer died "peacefully" at her Southern California ranch. She was best known for starring as Sandy in the 1978 film, appearing opposite John Travolta, who played Danny Zuko. Travolta led tributes, saying her "impact was incredible", signing off his social media post as "your Danny".